This invention relates to a safety plug for an electrical cord, particularly where the electrical cord is utilized for electrical devices in a household environment where the plug is plugged into a conventional wall socket.
The safety plug of this invention can be utilized in any environment, but is particularly adapted for use in a household where an electrical plug may become partially dislodged and expose active prong members to children. The safety plug of this invention is designed with a retractable safety shield on each of the two electrically active prongs of the electrical plug. The two safety shields in the form of individual sheaths retract as the prongs are inserted into the socket holes of a conventional electrical socket. In addition to preventing inadvertent contact with partially exposed prongs, the safety shields protect against inadvertent contact with the prongs upon extraction of an electrical plug from a socket. This is particularly important where small children are present. Children, particularly very young children, have a tendency to extract an electrical plug from a wall socket by placing fingers over the end of the partially extracted plug. This can result in a severe shock and burn.
Prior solutions for construction of a safety plug have included accordion-type outer coverings and retractable covers that utilize a shield housing that encompasses both prongs as a unit. The former type of protective means requires an insulator material that will repeatedly collapse in accordion fashion and not crack or lose its shape or resilience. Furthermore, the external accordion type sheath requires extra-long prongs to accommodate for the collapsed shielding material that compiles at the base of the prongs. This can destabilize the seating of the electrical plug and the added length of the prongs provides an additional danger during plugging and unplugging resulting from additional instability in the structure of the plug.
The electrical plugs that have a unitary housing that acts as a shield for simultaneous protection of both prongs customarily includes a spring mechanism located in the body of the plug between the two electrically active prongs. Locating an electrically conductive wire spring between electrically active prong members is somewhat dangerous in the event that the plug becomes damaged and the spring creates an electrical short between the two prong members. Additionally, the use of a single housing for both prongs will cause exposure of a prong when the plug is oriented at an angle where one prong is inserted into the socket at a greater depth than the other prong. In this orientation, the unitary housing is retracted to the insertion point of the more deeply inserted prong allowing a portion of the other prong to be exposed.
Finally, the use of a single shield for both prongs prevents easy visual identification of the location of the two prongs for proper orientation of the plug during insertion of the plug into a socket. These and other problems with the existing safety plugs have made the improved safety plug as disclosed herein a superior design with unique design features not incorporated in prior art devices.
It is a primary object of this invention to provide a safety plug that includes a retractable insulator sheath on each of the two electrical power prongs of an electrical plug. It is a further object of this invention to provide an independent spring bias to each of the two retractable sheaths and to position the biassing spring on the outside of each of the prongs to prevent inadvertent shorting when a metal spring is used.
Finally, it is an object of this invention to include a third prong that is positioned for orientation into the third prong socket in a conventional three prong electrical outlet. This prong assists in stabilizing the plug and engagement of this prong in the socket assists in preventing the shield plug from becoming ejected or withdrawn from the socket as a result of bias from the springs of the retracted sheaths and dislodgement by inadvertent contact of the plug while installed in the socket.